WINETECH Technical Yearbook 2021

conditions. Molecules 22(7). https://doi. org/10.3390/molecules22071164. Feuillat, M., 2003. Yeast macromolecules: Origin, composition and enological interest. American Journal of Enology and Viticulture 54(3): 211 LP-213. Linthorst , H.J.M. & Van Loon, L.C. , 1991. Pathogenesis related proteins of plants. CRC Critical Reviews in Plant Sciences 10(2): 123-150. https://doi. org/10.1080/07352689109382309. Ndlovu, T., Buica, A. & Bauer, F.F., 2019. Chitinases and thaumatin-like proteins in Sauvignon blanc and Chardonnay musts during alcohol ic fermentat ion. Food Microbiology 78 (December): 201-210. https://doi.org/10.1016/j.fm.2018.10.018.

role in haze formation in wine. Journal of Agricultural and Food Chemistry 58(2): 975- 980. https://doi.org/10.1021/jf902843b. Vincenzi, S., Marangon, M., Tolin, S. & Curioni, A., 2011. Protein evolution during the early stages of white winemaking and its relations with wine stability. Australian Journal of Grape and Wine Research 17(1): 20-27. https://doi.org/10.1111/j.1755- 0238.2010.00113.x. Marangon, M., Van Sluyter, S.C., Neilson, K.A., Chan, C., Haynes, P.A., Waters, E.J. & Falconer, R.J., 2011. Roles of grape thaumatin-like protein and chitinase in white wine haze formation. Journal of Agricultural and Food Chemistry 59(2): 733-740. https:// doi.org/10.1021/jf1038234. Sauvage, F.X., Bach, B., Moutounet, M. & Vernhet, A., 2010. Proteins in white wines: Thermo-sensitivity and differential adsorbtion by bentonite. Food Chemistry 118(1): 26-34. https://doi.org/10.1016/j. foodchem.2009.02.080. Tian, B., Harrison, R., Morton, J., Jaspers, M., Hodge, S., Grose, C. & Trought, M., 2017. Extraction of pathogenesis-related proteins and phenolics in Sauvignon blanc as affected by grape harvesting and processing

This study highlights that there is no correlation between total protein content and protein haze formation. A high total protein content in a juice does not translate to a higher risk of protein instability. It is the quantity of the PR proteins (especially grape chitinases) (Tian et al ., 2017) that are important and directly correlated to the protein haze formation. CONCLUSION Specific yeast strains hold significant potential to decrease the concentration of haze-forming proteins (particularly chitinase) in wines. The commercialisation of these types of yeast might significantly reduce the bentoni te requirements thereby minimising the volume lost due to sedimentation. The development of these yeasts would be especially advantageous in the production of Sauvignon blanc wines where protein instabilities and haze formation are often a challenge. REFERENCES Monteiro, S., Barakat, M., Piçarra-Pereira, M.A., Teixeira, A.R. & Ferreira, R.B., 2003. Osmotin and thaumatin from grape: A putative general defense mechanism against

pathogenic fungi. Phytopathology 93(12): 1505-1512. https://doi .org/10.1094/ PHYTO.2003.93.12.1505. Girbau, T. & Stummer, B., 2008. The effect of Uncinula necator (powdery mildew) and Botrytis cinerea infection of grapes on the levels of haze-forming pathogenesis-related proteins in grape juice. Australian Journal of Grape and Wine Research 1992: 14-22. Tian, B., Harrison, R., Jaspers, M. & Morton, J., 2015. Influence of ultraviolet exclusion and of powdery mi ldew infection on Sauvignon blanc grape composition and on extraction of pathogenesis-related proteins into juice. Australian Journal of Grape and Wine Research 21(3): 417-424. https://doi. org/10.1111/ajgw.12135. Ferreira, R.B. , Piçarra-Pereira, M.A. , Monteiro, S., Loureiro, V.B. & Teixeira, A.R., 2001. The wine proteins. Trends in Food Science and Technology 12(7): 230- 239. https://doi .org/10.1016/S0924- 2244(01)00080-2. Falconer, R.J., Marangon, M., Van Sluyter, S.C., Neilson, K.A., Chan, C. & Waters, E.J., 2010. Thermal stability of thaumatin-like protein, chitinase and invertase isolated from Sauvignon blanc and Semillon juice and their

For more information, contact Carien Coetzee at carien@basicwine.co.za.

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